My husband coined this Panera's copycat, but according to him this White Cheddar Macaroni and Cheese is way better!
Boil the pasta according to the package direction, reserving a cup of pasta water.
In a large skillet, melt butter over medium heat, whisk in flour and continue stirring for 3-5 minutes until the roux starts to become fragrant and golden.
Slowly pour in the milk, while whisking constantly until completely smooth, continue stirring until the sauce thickens. Remove from the heat, add in all the cheese and stir until it's all melted.
Stir in the pasta, along with a couple of tablespoons of the reserved pasta. Continue adding more pasta water until it reaches a creamy consistency. Serve immediately.